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November 11, 2006

How far should the couch be from the TV

How close should the couch be to the TV?


Sit too close to your big screen TV and you will be able to see the image build-up structure - scanning lines or pixels forming the image – thus distracting your attention and spoiling your home theater experience. Yet, sit too far away, and the impact will be lost.

There are differing opinions on the best way to determine the optimum TV viewing distance for a specific screen size. Just go to the movie theater and you will soon realize that it is all a question of personal preference - some would sit at the very back. Others would go straight to the front row, as they prefer the bigger picture and a wider angle of view, while some would simply choose their seat randomly somewhere in between these two extremes. The truth is that there are no scientific rules her. This does not mean that there aren't any guidelines that you should follow when planning a big screen purchase or a would-be home theater room.

SMPTE Recommendations and the THX Certification standards:


The Society of Motion Pictures and Television Engineers (SMPTE) recommends that the screen size for home theater use should occupy a 30 degrees field of view - in the horizontal plan - for the audience. Alternatively, the ideal TV viewing distance should be such that the screen width occupies an angle of 30 degrees from the viewing position.

This 30-degrees viewing angle seems to have been accepted by many as the standard in home theater and motion picture viewing. This SMPTE guideline is also in line with the THX certification standards in that these recommend that the back row of seats should have at least a 26 degrees viewing angle and while recommending an optimum viewing angle of 36 degrees. It is believed that within these viewing angle limits, the viewer will get better immersed into the action movie itself.

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November 10, 2006

Speakers make a humming sound

A humming sound coming from your speakers is really irritating. Here is an easy way to fix it.

You've all heard it, that dreaded 60Hz hum through the speakers of a home theater or house audio system. Hopefully you heard it at a friend's house and not your own. It can drive you completely nuts. You may have even tried, unsuccessfully, to fix the little noise problem. That can make you even more crazy. What causes that horrendous noise through your speakers?

More often than not humming through your speakers is caused by a grounding problem. There are three main ground problems that cause problems in an audio / video system. These are ground loops, improper grounding and lack of a ground altogether. The other possible culprits that can cause noise are bad cables, a faulty piece of equipment or electrical noise from a lighting dimmer or electric motor. There are steps you can take to troubleshoot the noise and eliminate it from you theater.

The first step is find out where it is coming from. Disconnect your source and display equipment from your receiver or surround sound processor. If the noise stops, connect them back to the receiver or processor on at a time until the noise returns. When the hum comes back, you found where the noise is entering your system. Note that if you are connecting remote equipment, such as running the signal from your theater room DVD player to the TV in the bedroom, your chances to pick up noise increase dramatically. With such long runs, noise can be induced into the long cable runs from adjacent electrical wiring. It is also easy to create a ground loop, because the equipment is plugged into two different, widely separated outlets, on different electrical circuits.

If the noise is caused by a cable box, the noise is likely caused by the cable TV ground. To test this theory, disconnect the incoming cable TV feed to the rear of the cable box or TV while they are still connected to the rest of the system. If the noise is eliminated by disconnecting the TV cable, the problem is the cable TV ground. You can electrically decouple the cable TV feed from your system with a ground breaking transformer. These are available from many sources. Be advised that many newer, digital cable TV systems require any device in the signal chain to pass a full 1,000 Mhz. Some of the older ground break transformers will not do this. Be sure to check the specifications of whatever device you are purchasing to verify it will pass the digital cable TV signal.

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